Often more than not your choice of shrubs will be performing as you expected them to but from time to time your garden may experience bouts of illness. A result of a Parasite, a Fungal Infection or a Virus. It can often is exarcerbated by humidity and wet weather.
Rot can set in if roots sit in saturated soil and grass can appear matted, soaked and flat. A lawn can generally speaking is kept in good order if following steps are considered. Most of us have a typical utility lawn which can become compacted as a result of constant traffic, neglect and adverse weather.
By aerating the lawn simply with the tines of a fork air can circulate under the surface and improve the drainage of the area. On a larger scale land drains can be installed by way of a trench, corrugated plastic piping and gravel in the trench.
Making sure the grass is not cut too short. If it is an amenity area the seed is fit for purpose (it will contain premium seed: Festcues and Bents). A typical lawn contains Ryegrass and Annual meadow grass and although more robust and resilient can only be mowed to a certain height. It has not been designed for a very short habit and only cut with a rotary mower.
If you weed and feed each year, only use moss killer and fertiliser moderately. Excessive application will be indicative by black marks. If you’re not fussy it will grow back and knit together or can be patched up by removing the affected area.
Regular inspection of your plants will often raise an alert if necessary. If there are notches missing off the leaves, if they are unexpectedly wilting or lost their colour and vigour. If a pattern is emerging throughout the bed, it may be a sign of a cross infection. To identify what it is, it is half the battle! There are organic (non biological and non chemical) and biological and chemical forms of treatment. For a bout of aphids on Roses, Soapy water can often work since the insects cannot stay on the leaves thereby minimising the damage. By growing resistant crops like carrots or beans can minimise the likelihood of verticullum wilt attacking a bed.
Leather Jackets/Chafer Grubs are a problem for lawn and young shrubs or vegetables. They attack the root system and although live under the surface are close to soil level and can be identified just short of the roots.
Vine Weevils are one the most common culprits, a black beetle which has yellow speckles and can be identified as the problem when the leaves show notches eaten. The seem to host themselves in the ground and prowl about causing destruction at night-time. Pesticides can be used or now there are “nematodes” available these predators will eat the problem away. It is worth noting that the majority of the time they invade on Shrubs in containers.
Verticullum Wilt can also be identified by a sudden setback of growth and appearance of dieback. It harbours itself in infected soil and penetrates through minor wounds or fine roots where their is weakness. It will last one year hosting on tissue so older plants usually recover. Younger ones, however, do not. If you experience a spate of this it is probably not worth putting a replacement in the same location since the fungus will remain in the soil. If you can cut into the tissue you will see a clear discolouration of an infected side and a healthy side.
Camellia’s suffer a mottle virus which produces yellow patches randomly on leaves. Research has shown it is not an insect but has evolved as a result of an infected knife/dirty secateurs. A lot of the time you can minimise these ailments but not eliminate them entirely. The list is extensive and sometimes linked to one particular Shrub. Good Practice should include clean tools, regular spraying if clearly susceptible to a particular condition, removing dead or diseased growth, regular feed and perhaps mulching in the colder months will all help.
Rust and Black spot can be particularly frustrating since it can inflict itself significantly quickly with Roses and on the undersides of the leaves you’ll notice orange spots. They will appear black in Autumn, reproduce and worsen the infection. By adding mulch around the crown in Winter and adopting a spraying programme you can keep these symptoms in abeyance.
Black spot does tend to affect Roses although it is known to attack other shrubs. A yellow -tinged black spot surrounded by a yellow lip. The leaves suffer chlorosis (discolouration) and die. This is usually in high humid, wet weather. Cutting out the diseased growth is the 1st step to its containment. Good housekeeping can help enormously, the debris being removed from the area and preventative spraying before the outbreak.
Viruses seem more difficult to diagnose and can only be sourced by poor management of tools, these should be cleaned regularly and thoroughly to avoid cross infection.
Viruses are usually carried by sucking insects like Aphids, leafhoppers and whitefly. Often agricultural crops will be chosen on their resistance merit as it is not uncommon for whole crops to be decimated.